Displays with Reduced Driver Circuit Ledges

ABSTRACT

An electronic device display may have a color filter layer, a thin-film-transistor layer, and a layer of liquid crystal material. The display may have a display cover layer such as a layer of glass or plastic. Adhesive may be used to attach the upper polarizer to the display cover layer. The thin-film transistor layer may have a substrate with upper and lower surfaces. Thin-film-transistor circuitry may be formed on the upper surface. A display driver integrated circuit may be mounted to the lower surface or a flexible printed circuit and may be coupled to the thin-film-transistor circuitry using wire bonding wires. Through vias that are formed through the thin-film-transistor layer substrate may be used in coupling the thin-film-transistor circuitry to the display driver integrated circuit.

This application is a continuation of U.S. patent application Ser. No.13/600,862, filed Aug. 31, 2012, which is hereby incorporated byreference herein in its entirety. This application claims the benefit ofand claims priority to U.S. patent application Ser. No. 13/600,862,filed Aug. 31, 2012.

BACKGROUND

This relates generally to electronic devices, and more particularly, toelectronic devices with displays.

Electronic devices often include displays. For example, cellulartelephones and portable computers often include displays for presentinginformation to a user. An electronic device may have a housing such as ahousing formed from plastic or metal. Components for the electronicdevice such as display components may be mounted in the housing.

It can be challenging to incorporate a display into the housing of anelectronic device. Size and weight are often important considerations indesigning electronic devices. If care is not taken, displays may bebulky or may be surrounded by overly large borders.

It would therefore be desirable to be able to provide improved displaysfor electronic devices.

SUMMARY

An electronic device may be provided with a display having upper andlower polarizers. The display may have a color filter layer, athin-film-transistor layer, and a layer of liquid crystal materialinterposed between the color filter layer and the thin-film-transistorlayer. The color filter layer and thin-film-transistor layer may beinterposed between the upper and lower polarizers. The display may havea display cover layer such as a layer of glass or plastic. Adhesive maybe used to attach the upper polarizer to the display cover layer.

The thin-film transistor layer may have a substrate such as a layer ofglass with opposing upper and lower surfaces. Thin-film-transistorcircuitry may be formed on the upper surface. A display driverintegrated circuit may be mounted to the lower surface or may be mountedto a flexible printed circuit. Wire bonding wires may be used to couplethe thin-film-transistor circuitry to a display driver integratedcircuit on the lower surface or may be used to couple thethin-film-transistor circuitry to a flexible printed circuit to which adisplay driver integrated circuit has been mounted.

Through vias may be formed through the thin-film-transistor layersubstrate. The through vias may be used in coupling a display driverintegrated circuit to the thin-film transistor circuitry or may be usedto couple the thin-film-transistor circuitry to a flexible printedcircuit to which a display driver integrated circuit is mounted.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative electronic device suchas a laptop computer with a display in accordance with an embodiment ofthe present invention.

FIG. 2 is a perspective view of an illustrative electronic device suchas a handheld electronic device with a display in accordance with anembodiment of the present invention.

FIG. 3 is a perspective view of an illustrative electronic device suchas a tablet computer with a display in accordance with an embodiment ofthe present invention.

FIG. 4 is a schematic diagram of an illustrative electronic device witha display in accordance with an embodiment of the present invention.

FIG. 5 is a cross-sectional side view of an illustrative display inaccordance with an embodiment of the present invention.

FIG. 6 is a cross-sectional side view of an illustrative display havingwire bond connections that have been used to interconnectthin-film-transistor circuitry on the upper surface of athin-film-transistor layer with flexible printed circuit structures onthe lower surface of the thin-film transistor layer in accordance withan embodiment of the present invention.

FIG. 7 is a cross-sectional side view of an illustrative display inwhich a driver integrated circuit has been mounted on the lower surfaceof a thin-film-transistor layer and in which wire bond connections havebeen used to connect thin-film-transistor circuitry on the upper surfaceof the thin-film-transistor layer to the driver integrated circuit inaccordance with an embodiment of the present invention.

FIG. 8 is a cross-sectional side view of an illustrative electronicdevice having a display in which a flexible printed circuit bus is beingused to connect a driver integrated circuit to traces on an uppersurface of a thin-film-transistor layer and in which optically clearadhesive is being used to attach display layers to a cover glass layerin accordance with an embodiment of the present invention.

FIG. 9 is a cross-sectional side view of an illustrative display inwhich through vias pass from the upper surface to the lower surface ofthe thin-film-transistor layer and in which a display driver circuit iscoupled to the vias using a flexible printed circuit in accordance withan embodiment of the present invention.

FIG. 10 is a cross-sectional side view of an illustrative display inwhich through vias pass from the upper surface to the lower surface ofthe thin-film-transistor layer and in which a display driver circuit ismounted to the vias on the lower surface in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION

Electronic devices may include displays. The displays may be used todisplay images to a user. Illustrative electronic devices that may beprovided with displays are shown in FIGS. 1, 2, and 3.

FIG. 1 shows how electronic device 10 may have the shape of a laptopcomputer having upper housing 12A and lower housing 12B with componentssuch as keyboard 16 and touchpad 18. Device 10 may have hinge structures20 that allow upper housing 12A to rotate in directions 22 aboutrotational axis 24 relative to lower housing 12B. Display 14 may bemounted in upper housing 12A. Upper housing 12A, which may sometimesreferred to as a display housing or lid, may be placed in a closedposition by rotating upper housing 12A towards lower housing 12B aboutrotational axis 24.

FIG. 2 shows how electronic device 10 may be a handheld device such as acellular telephone, music player, gaming device, navigation unit, orother compact device. In this type of configuration for device 10,housing 12 may have opposing front and rear surfaces. Display 14 may bemounted on a front face of housing 12. Display 14 may, if desired, havea display cover layer or other exterior layer that includes openings forcomponents such as button 26. Openings may also be formed in a displaycover layer or other display layer to accommodate a speaker port (see,e.g., speaker port 28 of FIG. 2).

FIG. 3 shows how electronic device 10 may be a tablet computer. Inelectronic device 10 of FIG. 3, housing 12 may have opposing planarfront and rear surfaces. Display 14 may be mounted on the front surfaceof housing 12. As shown in FIG. 3, display 14 may have a cover layer orother external layer (e.g., a color filter layer or thin-film-transistorlayer) with an opening to accommodate button 26 (as an example).

The illustrative configurations for device 10 that are shown in FIGS. 1,2, and 3 are merely illustrative. In general, electronic device 10 maybe a laptop computer, a computer monitor containing an embeddedcomputer, a tablet computer, a cellular telephone, a media player, orother handheld or portable electronic device, a smaller device such as awrist-watch device, a pendant device, a headphone or earpiece device, orother wearable or miniature device, a television, a computer displaythat does not contain an embedded computer, a gaming device, anavigation device, an embedded system such as a system in whichelectronic equipment with a display is mounted in a kiosk or automobile,equipment that implements the functionality of two or more of thesedevices, or other electronic equipment.

Housing 12 of device 10, which is sometimes referred to as a case, maybe formed of materials such as plastic, glass, ceramics, carbon-fibercomposites and other fiber-based composites, metal (e.g., machinedaluminum, stainless steel, or other metals), other materials, or acombination of these materials. Device 10 may be formed using a unibodyconstruction in which most or all of housing 12 is formed from a singlestructural element (e.g., a piece of machined metal or a piece of moldedplastic) or may be formed from multiple housing structures (e.g., outerhousing structures that have been mounted to internal frame elements orother internal housing structures).

Display 14 may be a touch sensitive display that includes a touch sensoror may be insensitive to touch. Touch sensors for display 14 may beformed from an array of capacitive touch sensor electrodes, a resistivetouch array, touch sensor structures based on acoustic touch, opticaltouch, or force-based touch technologies, or other suitable touch sensorcomponents.

Displays for device 10 may, in general, include image pixels formed fromlight-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells,electrowetting pixels, electrophoretic pixels, liquid crystal display(LCD) components, or other suitable image pixel structures. In somesituations, it may be desirable to use LCD components to form display14, so configurations for display 14 in which display 14 is a liquidcrystal display are sometimes described herein as an example. It mayalso be desirable to provide displays such as display 14 with backlightstructures, so configurations for display 14 that include a backlightunit may sometimes be described herein as an example. Other types ofdisplay technology may be used in device 10 if desired. The use ofliquid crystal display structures and backlight structures in device 10is merely illustrative.

A display cover layer may cover the surface of display 14 or a displaylayer such as a color filter layer, thin-film transistor layer or otherportion of a display may be used as the outermost (or nearly outermost)layer in display 14. For example, a color filter layer or thin-filmtransistor layer that is covered by a polarizer layer may form theoutermost layer for device 10. A display cover layer or other outerdisplay layer may be formed from a transparent glass sheet, a clearplastic layer, or other transparent member.

Touch sensor components such as an array of capacitive touch sensorelectrodes formed from transparent materials such as indium tin oxidemay be formed on the underside of a display cover layer, may be formedon a separate display layer such as a glass or polymer touch sensorsubstrate, or may be integrated into other display layers (e.g.,substrate layers such as a thin-film transistor layer).

A schematic diagram of an illustrative configuration that may be usedfor electronic device 10 is shown in FIG. 4. As shown in FIG. 4,electronic device 10 may include control circuitry 29. Control circuitry29 may include storage and processing circuitry for controlling theoperation of device 10. Control circuitry 29 may, for example, includestorage such as hard disk drive storage, nonvolatile memory (e.g., flashmemory or other electrically-programmable-read-only memory configured toform a solid state drive), volatile memory (e.g., static or dynamicrandom-access-memory), etc. Control circuitry 29 may include processingcircuitry based on one or more microprocessors, microcontrollers,digital signal processors, baseband processors, power management units,audio codec chips, application specific integrated circuits, etc.

Control circuitry 29 may be used to run software on device 10, such asoperating system software and application software. Using this software,control circuitry 29 may present information to a user of electronicdevice 10 on display 14. When presenting information to a user ondisplay 14, sensor signals and other information may be used by controlcircuitry 29 in making adjustments to the strength of backlightillumination that is used for display 14.

Input-output circuitry 30 may be used to allow data to be supplied todevice 10 and to allow data to be provided from device 10 to externaldevices. Input-output circuitry 30 may include communications circuitry32. Communications circuitry 32 may include wired communicationscircuitry for supporting communications using data ports in device 10.Communications circuitry 32 may also include wireless communicationscircuits (e.g., circuitry for transmitting and receiving wirelessradio-frequency signals using antennas).

Input-output circuitry 30 may also include input-output devices 34. Auser can control the operation of device 10 by supplying commandsthrough input-output devices 34 and may receive status information andother output from device 10 using the output resources of input-outputdevices 34.

Input-output devices 34 may include sensors and status indicators 36such as an ambient light sensor, a proximity sensor, a temperaturesensor, a pressure sensor, a magnetic sensor, an accelerometer, andlight-emitting diodes and other components for gathering informationabout the environment in which device 10 is operating and providinginformation to a user of device 10 about the status of device 10.

Audio components 38 may include speakers and tone generators forpresenting sound to a user of device 10 and microphones for gatheringuser audio input.

Display 14 may be used to present images for a user such as text, video,and still images. Sensors 36 may include a touch sensor array that isformed as one of the layers in display 14.

User input may be gathered using buttons and other input-outputcomponents 40 such as touch pad sensors, buttons, joysticks, clickwheels, scrolling wheels, touch sensors such as sensors 36 in display14, key pads, keyboards, vibrators, cameras, and other input-outputcomponents.

A cross-sectional side view of an illustrative configuration that may beused for display 14 of device 10 (e.g., for display 14 of the devices ofFIG. 1, FIG. 2, or FIG. 3 or other suitable electronic devices) is shownin FIG. 5. As shown in FIG. 5, display 14 may include backlightstructures such as backlight unit 42 for producing backlight 44. Duringoperation, backlight 44 travels outwards (vertically upwards in theorientation of FIG. 5) and passes through display pixel structures indisplay layers 46. This illuminates any images that are being producedby the display pixels for viewing by a user. For example, backlight 44may illuminate images on display layers 46 that are being viewed byviewer 48 in direction 50.

Display layers 46 may be mounted in chassis structures such as a plasticchassis structure and/or a metal chassis structure to form a displaymodule for mounting in housing 12 or display layers 46 may be mounteddirectly in housing 12 (e.g., by stacking display layers 46 into arecessed portion in housing 12). Display layers 46 may form a liquidcrystal display or may be used in forming displays of other types.

In a configuration in which display layers 46 are used in forming aliquid crystal display, display layers 46 may include a liquid crystallayer such a liquid crystal layer 52. Liquid crystal layer 52 may besandwiched between display layers such as display layers 58 and 56.Layers 56 and 58 may be interposed between lower polarizer layer 60 andupper polarizer layer 54.

Layers 58 and 56 may be formed from transparent substrate layers such asclear layers of glass or plastic. Layers 56 and 58 may be layers such asa thin-film transistor layer and/or a color filter layer. Conductivetraces, color filter elements, transistors, and other circuits andstructures may be formed on the substrates of layers 58 and 56 (e.g., toform a thin-film transistor layer and/or a color filter layer). Touchsensor electrodes may also be incorporated into layers such as layers 58and 56 and/or touch sensor electrodes may be formed on other substrates.

With one illustrative configuration, layer 58 may be a thin-filmtransistor layer that includes an array of thin-film transistors andassociated electrodes (display pixel electrodes) for applying electricfields to liquid crystal layer 52 and thereby displaying images ondisplay 14. Layer 56 may be a color filter layer that includes an arrayof color filter elements for providing display 14 with the ability todisplay color images. If desired, the positions of color filter layer 56and thin-film-transistor layer 58 may be inverted so that thethin-film-transistor layer is located above the color filter layer.

During operation of display 14 in device 10, control circuitry 29 (e.g.,one or more integrated circuits such as components 68 on printed circuit66 of FIG. 5) may be used to generate information to be displayed ondisplay 14 (e.g., display data). The information to be displayed may beconveyed from circuitry 68 to display driver integrated circuit 62 usinga signal path such as a signal path formed from conductive metal tracesin flexible printed circuit 64 (as an example).

Display driver integrated circuit 62 may be mounted onthin-film-transistor layer driver ledge 82 or elsewhere in device 10. Aflexible printed circuit cable such as flexible printed circuit 64 maybe used in routing signals between printed circuit 66 andthin-film-transistor layer 60. If desired, display driver integratedcircuit 62 may be mounted on printed circuit 66 or flexible printedcircuit 64. Printed circuit 66 may be formed from a rigid printedcircuit board (e.g., a layer of fiberglass-filled epoxy) or a flexibleprinted circuit (e.g., a flexible sheet of polyimide or other flexiblepolymer layer).

Backlight structures 42 may include a light guide plate such as lightguide plate 78. Light guide plate 78 may be formed from a transparentmaterial such as clear glass or plastic. During operation of backlightstructures 42, a light source such as light source 72 may generate light74. Light source 72 may be, for example, an array of light-emittingdiodes.

Light 74 from light source 72 may be coupled into edge surface 76 oflight guide plate 78 and may be distributed laterally throughout lightguide plate 78 due to the principal of total internal reflection. Lightguide plate 78 may include light-scattering features such as pits orbumps. The light-scattering features may be located on an upper surfaceand/or on an opposing lower surface of light guide plate 78.

Light 74 that scatters upwards from light guide plate 78 may serve asbacklight 44 for display 14. Light 74 that scatters downwards may bereflected back in the upwards direction by reflector 80. Reflector 80may be formed from a reflective material such as a layer of whiteplastic or other shiny materials.

To enhance backlight performance for backlight structures 42, backlightstructures 42 may include optical films 70. Optical films 70 may includediffuser layers for helping to homogenize backlight 44 and therebyreduce hotspots, compensation films for enhancing off-axis viewing, andbrightness enhancement films (also sometimes referred to as turningfilms) for collimating backlight 44. Optical films 70 may overlap theother structures in backlight unit 42 such as light guide plate 78 andreflector 80. For example, if light guide plate 78 has a rectangularfootprint when viewed in direction 50 of FIG. 5 (i.e., when viewed as atop view), optical films 70 and reflector 80 may have a matchingrectangular footprint.

FIG. 6 is a cross-sectional side view of an illustrative configurationthat may be used for the structures of display 14 when it is desired tominimize the width of the inactive border region of the display 14. Asshown in FIG. 6, display 14 may have a ledge such as ledge 82 onthin-film-transistor layer 58 (i.e., a portion of layer 58 that isuncovered by color filter layer 56). The size of ledge 82 ofthin-film-transistor layer 58 may be minimized by mounting driverintegrated circuit 62 on flexible printed circuit 64.

Thin-film-transistor layer 58 may include an array of display pixels.The display pixels may be controlled by signals that are routed over agrid of intersecting gate lines and data lines. Each display pixel maycontain electrode structures for applying an electric field to anassociated portion of liquid crystal layer 52. Thin-film transistors maybe provided in the display pixels to control the electric fields thatare applied by the electrode structures. The thin-film transistors, gatelines, data lines, other conductive lines, and other thin-film circuitry(e.g., gate line driver circuitry) formed on the upper surface ofthin-film-transistor layer 58 is shown as thin-film-transistor circuitry106 of FIG. 6.

Circuitry 106 may be formed on a substrate such as substrate 108.Substrate 108 may be formed from a sheet of clear glass or plastic orother transparent dielectric layer. Substrate 108 may have opposingplanar upper and lower surfaces. Thin-film-circuitry 106 may be formedon the upper surface of substrate 108. Thin-film-circuitry 106 mayinclude conductive lines such as conductive gate lines and data linesand other conductive lines that are used in distributing signals onthin-film-transistor layer 58. Conductive lines on thin-film-transistorlayer 58 (e.g., metal traces or other conductive materials that areformed as part of thin-film-transistor circuitry 106 on the uppersurface of thin-film-transistor substrate 108) are shown as lines 96 inFIG. 6.

Display driver integrated circuits such as display driver integratedcircuit 62 of FIG. 6 may be mounted on substrates such as flexibleprinted circuit 64. Flexible printed circuit 64 may be attached to thelower surface of thin-film-transistor layer substrate 108 as shown inFIG. 6 or may be mounted to other support structures within device 10.

Flexible printed circuit 64 may include one or more layers of conductivelines 100 such as metal traces. Conductive lines 100 may serve as signallines that distribute signals between display driver integrated circuit62 and thin-film-transistor circuitry 106. Conductive lines 100 mayinclude parallel signal paths that form a signal bus. Each of conductivelines 100 may be coupled to a respective signal path such as one of wirebond wires 92.

Each wire bonding wire 92 may have opposing first and second ends. Thefirst end of each wire bonding wire 92 may be coupled to a respectiveone of traces 100 in flexible printed circuit 62 using a respective wirebond connection 98. The second end of each wire bonding wire 92 may beconnected to a respective one of traces 96 in thin-film-transistorcircuitry 106 on the upper surface of thin-film-transistor layersubstrate 108. Wire bonding wires (wire bonds) 92 may be formed using awire bonding tool. During wire bonding operations, the wire bonding headof the wire bonding tool and/or thin-film-transistor layer 58 may bepositioned so that wire bonds 92 extend from the upper surface ofthin-film-transistor layer 58 to the lower surface of thin-filmtransistor layer 58 (e.g., the exposed lower surface of flexible printedcircuit layer 64).

Black masking material 90 may be formed around the inactive periphery(border) of display 14 between color filter layer 56 andthin-film-transistor layer 58. Black masking material 90, which maysometimes be referred to as opaque masking material, may be formed froma polymer containing carbon black or other material that absorbs visiblelight. Black masking material 90 may be patterned to form a strip thatserves as an opaque border running around the rectangular periphery ofdisplay 14 overlapping inactive display components (e.g., display drivercircuitry, a thin-film-transistor ledge, etc.) and helping to hide thesecomponents from view by a viewer such as viewer 48 of FIG. 5. Blackmasking material 90 may be deposited in a rectangular ring shapesurrounding a central rectangular portion of display 14 that includesthe display pixels for display 14.

Another illustrative configuration that may be used in forming a displaywith a reduced inactive border region is shown in FIG. 7. As shown inFIG. 7, display driver circuitry such as one or more display driverintegrated circuits 62 may be mounted on the lower surface ofthin-film-transistor layer substrate 108. Conductive lines 102 may beformed on the lower surface of thin-film-transistor layer substrate 108(e.g., to form pads to which a flexible printed circuit cable may beattached). Wire bonding wires 92 may be used to form connections withdisplay driver integrated circuit 62 directly at connections such aswire bond connection 98 and/or may be used to form connections withdisplay driver integrated circuitry 62 by forming a connection such asconnection 98′ with lower surface conductive lines 102. Inconfigurations in which wire bonding wires 92 terminate on conductivelines 102, conductive lines 102 may be used to connect wires 92 todriver integrated circuit 62 (e.g., by using solder balls to flip-chipmount driver integrated circuit 62 to solder pads formed from conductivelines 102. Each wire bonding wire 92 may have a connection such as wirebond 94 of FIG. 7 with which that wire is connected to conductive lineson the upper surface of thin-film transistor layer 58.

As shown in the cross-sectional side view of FIG. 8, another way inwhich the size of thin-film-transistor layer driver ledge 82 may beminimized involves mounting a display driver integrated circuit 62 onflexible printed circuit 64 (e.g., using solder or other connectionsbetween the circuitry of integrated circuit 62 and conductive lines 100)and using conductive lines 100 in flexible printed circuit 64 to routesignals between display driver integrated circuit 62 and conductivelines 96 and other thin-film-transistor circuitry 106 on the uppersurface of thin-film-transistor substrate layer 108. Traces 100 may becoupled to traces 96 using conductive adhesive (anisotropic conductivefilm), welds, solder connections, board-to-board connectors, or otherattachment mechanisms. Because display driver integrated circuit 62 neednot be located on ledge 82 of thin-film-transistor layer 58, the size ofledge 82 (and therefore the width of the inactive border portion ofdisplay 14 in the vicinity of ledge 82) may be minimized.

Displays such as display 14 of FIG. 8 and other displays 14 for device10 may have an optional display cover layer such as display cover layer110. Display cover layer 110 may be formed from a layer of clear glass,a layer of transparent plastic, a layer of transparent ceramic, or othertransparent material. The thickness of display cover layer 110 may be,for example, 0.1 to 5 mm (as examples).

If desired, optically clear adhesive such as adhesive 104 may be used toattach display cover layer 110 to the outermost surface of upperpolarizer 54. When display cover layer 110 is attached to the layers ofdisplay 14 in this way, display cover layer 110 may exhibit a reducedlikelihood of cracking during use of device 10, allowing the thicknessof display cover layer 110 to be reduced. Display cover layer 110 may,if desired, be formed from a relatively hard material (e.g., glass) toresist scratching. Black masking layers 90 may be formed around theperiphery of display cover layer 110 to block internal device structuressuch as driver ledge 82 from view by a user of device 10.

If desired, via structures may be used to reduce or eliminate the needfor ledge 82 on thin-film-transistor layer 58. An illustrativeconfiguration for display 14 in which the width of the inactive borderfor the display has been minimized by eliminating thin-film-transistorledge 82 is shown in FIG. 9. As shown in FIG. 9, vias 112 may be formedbetween the upper and lower surfaces of thin-film-transistor layer 58.When routing signals through thin-film-transistor layer 58 in this way,ledge 82 may be eliminated.

Vias 112, which may sometimes be referred to as via structures, metalvias, or through vias, may be used to connect conductive lines inthin-film-transistor circuitry 106 such as conductive lines 96 to thecircuitry of flexible printed circuit 64 (e.g., to conductive lines inflexible printed circuit such as conductive lines 100). Vias 112 mayinclude holes that pass through substrate 108 and metal or otherconductive material that fully or partly fills the holes. Solder,conductive adhesive, or other conductive materials may be used to couplethe metal of vias 112 to the metal of conductive lines 100 in flexibleprinted circuit 64. Solder or other conductive materials may also beused in mounting driver circuitry such as display driver integratedcircuit 62 to traces 100 of flexible printed circuit 64.

Flexible printed circuit 64 may include one or more bends such asright-angle bend 114 of FIG. 9. With the illustrative configuration ofFIG. 9, flexible printed circuit 64 may have a portion that lies flat onthe lower surface of substrate 108 and a portion that extends away fromsubstrate 108 at a perpendicular angle (e.g., vertically downward in thearrangement of FIG. 9). This type of arrangement may allow displaydriver integrated circuit 62 to be mounted along the inner surface of ahousing sidewall in housing 12 of device 10.

Vias 112 may be formed by drilling openings in thin-film-transistorsubstrate 108 (e.g., using laser etching or other hole formationtechniques). Following the formation of openings in thin-film-transistorlayer substrate 108, metal or other conductive material may be formedwithin the openings (e.g., using physical vapor deposition, chemicalvapor deposition, electrochemical deposition, or other suitablefabrication techniques). If desired, vias 112 may be formed by embeddingmetal wires within thin-film-transistor layer 108 during glass formationoperations.

As shown in FIG. 10, display driver integrated circuit 62 may be mounteddirectly to the lower surface of thin-film-transistor substrate layer108. Solder, conductive adhesive, or other conductive material may beused in interconnecting the circuitry of display driver integratedcircuit 62 to the metal of vias 112. Metal pads may be formed on thelower surface of substrate 108 (e.g., on vias 112 or connected to vias112) and/or on display driver integrated circuit 62. Solder, conductiveadhesive, or other conductive material may be interposed between themetal pads on substrate 108 and on display driver integrated circuit 62.

The foregoing is merely illustrative of the principles of this inventionand various modifications can be made by those skilled in the artwithout departing from the scope and spirit of the invention.

What is claimed is:
 1. An organic light-emitting diode displaycomprising: a transparent display layer; a thin-film-transistor layerhaving a substrate with first and second opposing surfaces andthin-film-transistor circuitry formed on the first surface; and adisplay driver integrated circuit mounted to the second surface, whereinthe transparent display layer overlaps the display driver integratedcircuit, and wherein the substrate has conductive vias that pass throughthe substrate from the first surface to the second surface and thatcouple the thin-film-transistor circuitry to the display driverintegrated circuit.
 2. The organic light-emitting diode display definedin claim 1 wherein the transparent display layer comprises a layer ofdielectric material that at least partially overlaps thethin-film-transistor layer.
 3. The organic light-emitting diode displaydefined in claim 1 wherein the substrate comprises a plastic layer. 4.The organic light-emitting diode display defined in claim 1, wherein theconductive vias comprise laser-drilled holes.
 5. The organiclight-emitting diode display defined in claim 1, wherein the organiclight-emitting diode display has an active area surrounded by aninactive border region, and wherein at least one of the conductive viasis formed in the inactive border region.
 6. The organic light-emittingdiode display defined in claim 5, wherein the transparent display layeroverlaps the conductive vias.
 7. The organic light-emitting diodedisplay defined in claim 5 wherein at least one of the conductive viasoverlaps the display driver integrated circuit.
 8. The organiclight-emitting diode display defined in claim 7, wherein at least two ofthe conductive vias overlap the display driver integrated circuit.
 9. Adisplay, comprising: a thin-film-transistor layer having a substratewith first and second opposing surfaces and having thin-film-transistorcircuitry formed on the first surface; a flexible printed circuit havinga first portion that is mounted to the second surface and a secondportion that extends away from the second surface, wherein the first andsecond portions are connected by a bent portion of the flexible printedcircuit; and a display driver integrated circuit mounted to the secondportion of the flexible printed circuit, wherein the substrate hasconductive vias that pass through the substrate from the first surfaceto the second surface and that couple the thin-film-transistor circuitryto the flexible printed circuit.
 10. The display defined in claim 9wherein the second portion extends away from the second surface at anangle perpendicular to the second surface.
 11. The display defined inclaim 9 wherein the flexible printed circuit has first and secondopposing surfaces, wherein the first surface of the flexible printedcircuit is mounted to the second surface of the substrate, and whereinthe display driver integrated circuit is mounted to the second surfaceof the flexible printed circuit.
 12. The display defined in claim 9wherein the display is an organic light-emitting diode display.
 13. Thedisplay defined in claim 9 wherein the substrate has a first peripheraledge between the first and second opposing surfaces, wherein the layerof dielectric material has a second peripheral edge, and wherein thefirst and second peripheral edges are aligned.
 14. The display definedin claim 9 wherein the substrate is a plastic layer.
 15. A displaycomprising: a thin-film-transistor layer having a substrate with upperand lower surfaces and thin-film-transistor circuitry formed on theupper surface; a layer of transparent dielectric material that overlapsthe thin-film-transistor layer; and a display driver integrated circuitmounted directly to the lower surface, wherein the substrate hasconductive vias that pass through the substrate from the upper surfaceto the lower surface and that couple the thin-film-transistor circuitryto the display driver integrated circuit, and wherein at least one ofthe conductive vias overlaps the display driver integrated circuit. 16.The display defined in claim 15, further comprising: light-emittingstructures that emit light through the layer of transparent dielectricmaterial.
 17. The display defined in claim 15, wherein the display is anorganic light-emitting diode display.
 18. The display defined in claim15, wherein the substrate is a layer of plastic.
 19. The display definedin claim 15, wherein the display has an active area surrounded by aninactive border region.
 20. The display defined in claim 19, wherein thedisplay driver integrated circuit is mounted directly to the lowersurface in the inactive border region.